Check the plug connectors that relay gets plugged into. Since you used diffferent relays there, I would check the connector terminals; if all good check wiring going to the relay connector plug.
great suggestions as the different relays may have spread the terminals,
What type of relay??? Got a picture??
Is the relay sized properly for the load ?? A 30 amp draw should have a 45+ Amp relay IMO.
Some relays are rated for intermittent operation while others are continuous.
Take the cover off if possible and inspect the contacts twocents beer